A comparative study on the ferromagnetic properties of undoped and Mn-doped ZnO

We have investigated the origin of the ferromagnetic ordering in undoped and Mn-doped ZnO thin films. A systematic comparison is presented between two sets of films grown by pulsed laser deposition from targets prepared under the same conditions. We show that ferromagnetic ordering in both compounds is directly related to the concentration of oxygen vacancies. The incorporation of Mn dramatically increases the magnetic moment in highly oxygen-deficient films. By analyzing the photoluminescence spectra and the structural properties of the films, we can exclude that magnetic ordering in our films originates from unintentional doping.

► We compare the ferromagnetic properties of ZnO and Mn-doped ZnO films grown under the same conditions. ► The concentration of oxygen vacancies and Zn defects were monitored by Hall and photoluminescence measurements. ► The magnetic moment in ZnO and Mn-doped ZnO films increases with the increase of the concentration of oxygen vacancies. ► The incorporation of Mn dramatically increases the magnetic moment only in highly oxygen-deficient films.